NEW HAVEN, Conn. — A U.S. Army veteran who turned his life around after struggling with drug addiction is fighting his deportation, saying he should not have been expelled last year for a minor criminal record after honorably serving his country and living here legally for more than 50 years.

Arnold Giammarco was deported to his native Italy over drug possession and larceny convictions, his attorneys said. The former Connecticut resident is seeking to reverse his deportation, arguing in a federal lawsuit he planned to file Tuesday that immigration authorities never acted on his citizenship application in 1982.

Giammarco, 57, did brief stints in prison for shoplifting in the 1990s and drug possession in 2007. He has been homeless at times, but his supporters said he got clean, became a father in 2008, found work and married.

“I think it’s a shameful thing for the United States to take a man who’s lived lawfully in this country for 50 years, who’s raising a family, who’s working productively, who volunteered for the Army, served honorably,” said Michael Wishnie, a law professor at Yale University handling his case with law school students. “It’s a shameful thing to deport him based on minor non-violent criminal convictions. It’s a departure I think from our historic treatment of veterans.”

Giammarco served in the Army from 1976 to 1979 and National Guard from 1980 to 1983 and had a green card to live legally in the U.S., Wishnie said.

Khaalid Walls, a spokesman for U.S. Immigration and Customs Enforcement, declined to comment on the case. Immigration officials contend in documents obtained by Yale students working on the case that his application wasn’t completed.

ICE exercises prosecutorial discretion for veterans on a case-by-case basis when appropriate, Walls said. ICE issued a memo in 2011 that identifies military service as a positive factor that should be considered.

“We are very deliberate in our review of cases involving veterans,” Walls said.

For decades, authorities declined to deport veterans except in extraordinary circumstances but Giammarco’s lawyers say immigration agents have departed from that practice in recent years.

Giammarco’s grandfather returned to Italy after he was wounded in World War I fighting in the U.S. Army. Giammarco and his parents came to live in the U.S. in 1960 when he was 4.

Giammarco and his supporters say he’s had a tough time in Italy, with even relatives suspecting he must have committed a more serious crime to be deported after serving in the military. Giammarco, who spoke little Italian, eventually landed a part-time landscaping job.

“It was just a big nightmare,” Giammarco said in a telephone interview.

Giammarco, whose daughter turns 5 Tuesday, said he has missed three of her birthdays. His daughter asked him if he would be home for her birthday and Christmas.

Giammarco and his wife married on July 4, 2010, the 50th anniversary of his arrival with his parents in the United States. Giammarco’s wife, Sharon, has collected more than 3,000 signatures on a petition to officials seeking his return.

Giammarco was arrested by immigration officials in 2011 and was detained in a Massachusetts jail for 18 months before he was deported. His daughter visited him, but could not hug or touch him.

“I just wait for a day to hold my daughter again in the country that I love,” he said.